A Charlotte-Mecklenburg police officer who led some of the department’s youth programs has been charged with secretly taking pictures of girls’ underwear as they participated in physical activities in a program for youth curious about law enforcement careers.

Officer Thomas E. Allen, a CMPD officer for 18 years, was arrested Wednesday and charged with four counts of secretly using a photographic imaging device to view another’s body or undergarments, and with possessing the photographs, according to police.

Allen, 42, was interviewed by detectives Wednesday and later released from Mecklenburg jail on $15,000 bond. The department has begun proceedings to fire him, CMPD Chief Rodney Monroe said.

And police say they are trying to contact more than 700 students who participated in the department’s high school academy, Explorer Posts or other youth-oriented programs that Allen was involved in over the past 12 years to see whether similar incidents occurred.

“Allen’s behavior is totally unacceptable,” said CMPD Chief Rodney Monroe during a 22-minute news conference at police headquarters. “It violates the public trust. If we think one of our officers goes against the public’s trust ... we will use whatever resources we have available.

“We’re hoping that anyone who believes (Allen) may have had inappropriate contact will come forward and we will look to investigate.”

Monroe said the four victims were all girls between the ages of 14 and 18 participating in CMPD’s high school academy at the police training center in south Charlotte. Allen, who frequently photographed events for the department’s youth programs, took the pictures with a 35-millimeter camera while the girls were exercising, then kept the images.

Investigators have combed through “thousands and thousands of photos,” Monroe said. They found no child pornography and no further questionable photos, he said.

Allen could not be reached for comment on Wednesday. It is unclear if he has hired a lawyer. According to Monroe, he is married but has no children.

Allen has worked for CMPD since March 1996 and began working as a recruiter at the Police Training Academy in 2002. His annual salary is $67,876.38, according to city records.

He was involved in several programs the department runs for youth interested in police careers, including the department’s Explorers program and the CMPD High School Academy. He also was the department’s organizer of the Explorers Christmas Project for several years.

Explorers meet at the police academy for two hours twice a month to learn about various jobs in the police department.

The High School police academy is a weeklong program that puts teens through a mock academy, covering topics such as traffic stops, building searches, and “the responsibilities of wearing the badge,” according to the CMPD website. Students are also required to participate in basic physical fitness activities during the academy.

Monroe said the department takes photos of many such activities, and it was not unusual for an officer to photograph youth activities.

The investigation began in October. Monroe released few details on what started it, but said at least one of Allen’s supervisors had suspicions. More details were unearthed during subsequent interviews.

Allen’s arrest comes on the heels of another high-profile arrest of a police officer. Last September, Officer Randall Kerrick was charged with voluntary manslaughter in connection with the shooting of Jonathan Ferrell, an unarmed motorist who may have been looking for help after a car wreck.

In December 2010, former police officer Marcus Jackson pleaded guilty and was sentenced to two years in prison for sexually assaulting six women while on duty in 2009. Investigators say he assaulted people during traffic stops. Staff writer Steve Lyttle contributed.